title: Modulation of haemocyte phagocytic and antibacterial activity by alpha-adrenergic receptor in scallop Chlamys farreri.
abstract: The adrenergic receptors are a class of G protein-coupled receptors, through which norepinephrine and epinephrine trigger the second messenger to modulate the immune response in immunocytes of vertebrate. In the present study, a gene coding the homologue of α-adrenergic receptor was identified from scallop Chlamys farreri (designated CfαAR). Its deduced protein comprised 318 amino acids, and contained a conserved 7tm_1 domain. After CfαAR protein was expressed in the HEK293 cells, the stimulation of octopamine, tyramine, epinephrine and isoprenaline (β-adrenergic receptor agonist) did not change significantly the intracellular cAMP concentration, whereas the stimulation of norepinephrine and phenylephrine (α-adrenergic receptor agonist) lowered significantly the cAMP level to 0.52 and 0.84 pmol μl(-1) (P < 0.05), respectively. The CfαAR transcripts were ubiquitously detected in the tested tissues including haemocytes, adductor muscle, kidney, hepatopancreas, gill, gonad and mantle, with the highest expression in the gill. The expression level of CfαAR mRNA decreased significantly (0.21-fold, P < 0.05) at 3 h after the challenge of bacteria Vibrio anguillarum. Then, it began to increase (4.74-fold, P < 0.05) at 12 h, and reached the highest level (4.92-fold, P < 0.05) at 24 h after bacteria challenge. The addition of α-adrenergic receptor agonist to the primary scallop haemocytes repressed significantly the increase of phagocytic and antibacterial activity induced by LPS stimulation, while the induction was reverted by the addition of α-adrenergic receptor antagonist. These results collectively suggested that α-adrenergic receptor could be regulated dynamically in the transcriptional level during the immune response, and it could modulate the haemocyte phagocytic and antibacterial function through the second messenger cAMP, which might be requisite for pathogen elimination and the homeostasis maintenance in scallop.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhou
authors.forename: Qiufeng
authors.initials: Q
authors.lastname: Jiang
authors.forename: Mengqiang
authors.initials: M
authors.lastname: Wang
authors.forename: Feng
authors.initials: F
authors.lastname: Yue
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.forename: Leilei
authors.initials: L
authors.lastname: Wang
authors.forename: Fengmei
authors.initials: F
authors.lastname: Li
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism; D057809:HEK293 Cells; D006434:Hemocytes / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D049897:Pectinidae / Q000378:metabolism*; D010587:Phagocytosis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011942:Receptors, Adrenergic, alpha / Q000235:genetics / Q000378:metabolism*; D014733:Vibrio / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D011942:Receptors, Adrenergic, alpha; D000242:Cyclic AMP
keywords: Haemocyte; Immunomodulation; Scallop; cAMP; α-Adrenergic receptor